modrey



Feb. 2, 1960 H. J. MODREY 2,923,909

PLUG FOR AN ELECTRICAL CONNECTOR Filed March 5, 1956 A 1 l8 u k\ FIG. 9

FIG. IQ

INVENTOR.

HENRY J. MODREY Y MWM ATTORNEYS United States Patent PLUG FDR ANELECTRICAL CONNECTOR Henry J. Modrey, Stamford, Conn.

Application March 5, 1956, Serial No. 569,403

6 Claims. (Cl. 339-61) The present invention relates to two-partelectric Wire connectors, and more particularly to cord connectors. Asthe terminology used by the industry for component parts of electricalconnectors is not always consistent, the removable part of suchconnector which is generally attached to the cord, is hereafter referredto as plug, and the stationary part which is generally attached to orintegral with a base or housing, is referred to as receptacle.

An advantageous though not exclusive field of application of theinvention are cord connectors for electrical devices, especially devicesthe connector cord of which is or may be subjected to a pull tending toseparate the cord from the device when the latter is in use. Devices ofthis kind are for instance, portable tools, appliances and electricshavers. The tendency towards involuntary separation is aggravated ifthe cord used is of the springy coiled type. Another field ofapplication of the invention are electric connectors in which turning ofone member relative to the other effects a positive lock.

Cords of the general kind above referred to, frequently terminate at theend to be connected to the appliance or other device in a plug attachedto or molded integrally with the insulation material of the cord andhaving two tubular outlet contacts. The receptacle on the devicegenerally comprises two or more contacts, frequently set in'& well orrecess in the body of the device. Contact and mechanical retention areobtained by the friction between the engaging contact elements of theplug and 'the receptacle. Experience shows that this frictionalretention materially deteriorates by repeated connection anddisconnection. As a result, the contact pressure decreasescorrespondingly and finally the cord plug is no longer safely retained.

Accordingly, one of the objects of the invention is to provide a noveland improved plug which is more safely -yet releasably retained in thereceptacle of the appliance or' device.

Another object of the invention is to provide a novel 'and improved plugwhich affords substantially constant contact pressure for a prolongedperiod of use. j

Still another object of the invention is to provide a novel and improvedinterchangeable plug designedto coact with receptacles of conventionaldesign.

The expression conventional design shall be deemed to describeelectrical connectors which have found widespread acceptance, withcontact members in the shape of pins or fiat prongs. It shall be deemedto include connectors with flat, curved hooloshaped contact members inwhich turning of the plug relative to the receptacle effects a positivelock. The interchangeability of the plugs according to the inventionaffords the advantage "that the plug can be readily used instead of aplug of conventional design without alteration of the conventionalreceptacles.

A further and more general object of the invention is :to' provide anovel and improved plugwhich can be strongly secured to the receptacleof an electric connector ice by temporary deformation of a component ofthe plug according to the invention, and can be released by similartemporary deformation of the same component.

Other and further objects, features and advantages of the invention willbe pointed out hereinafter and set forth in the appended claims formingpart of the application.

In the accompanying drawing several preferred embodiments of theinvention are shown by way of illustration and not by way of limitation.

In the drawing:

Fig.- 1 is a sectional view of a plug according to the invention and ofa receptacle of conventional design coacting with the plug of theinvention.

Fig. 2 is a section taken on line 22 of Fig. 1.

Fig. 3 is an isometric view of a modification of the plug according tothe invention and a plan view of the application of this plug to areceptacle of conventional design.

Fig. 4 is a section taken on line 4-4 of Fig. 3.

Fig. 5 is a sectional view of a locking plug and receptacle according tothe invention.

Fig. 6 is a fragmentary view showing the contact elements of Fig. 5applied to each other on an enlarged scale, the view of Fig. 6 beingturned through Fig. 7 is a modification of the plug of Figs. 5 and 6,shown partly in section.

Fig. 8 is a locking plug according to the invention, designed forreceiving flat, curved, hook shaped contact elements.

Fig. 9 is a locking receptacle of conventional design comprising flat,curved, hook-shaped contact elements, for coaction with the locking plugshown in Fig. 8.

I Fig. 10 is a fragmentary isometric sectional view of the contactelements of Figs. 8 and 9 applied to each other. I-

Fig. 11 shows a tool suitable for the manufacture of plugs as shown forinstance in Figs. 1, 3 and 5; and

Fig. 12 shows a tool for producing a plug as show for instance in Fig.8.

Referring first in detail to Figs. 1 and 2, the two-part connector shownin these figures comprises a plug according to the invention generallydesignated by 15 and applicable to a receptacle generally designated by16; vReceptacle 16 is of conventional design. It is shown as com.-prising a housing 17 in which is seated an insulation disc 18 mountingtwo contact pins 19 shown as being of the round pin type.

The plug comprises a body 20 made of rubber or other suitable elasticmaterial. Body 20 may be molded integrally with the insulation of thewires. Two contact sleeves 21 for receiving contact pins 19 are fittedin .body 20 in electric contact with cord wires 22 and 23. The sleevesend short of the forward face of body 20 and bores 24 extend from theforward face to the sleeves. Bores 24 and sleeves 21 are axiallymisaligned when body 20 is in its normal relaxed condition which is thecondition shown. 7

Let it now be assumed that it is desired to apply plug .15 to receptacle16. To this end the forward part of body 20, that is, the part includingbores 24 is inserted into housing 17. Pins 19 will enter holes 24 butfurther insertion is blocked by abutment of the tips of pins 19 with theedges of the misaligned contact sleeves. To complete the insertion ofplug 15, the rear part thereof, that is, the part including sleeves 21is circumferentially turned relative to the front part which is heldstationary by the engagement of pins 19 with bores 24. This stretchesand elongates bores 24. As soon as sleeves 21 and bores 24 have reacheda position of axial alignment, ingress is no longer blocked and the plugcan be pushed home.

As is evident, the torsion applied to the rearpart of body 20 storespotential energy in the body due to the elasticity of the body material.Consequently, the tensioned rear part of the body when released seeks tounwind itself and to return into its initial or relaxed positionrelative to the front part. However, the insertion of the contact pinspermits a partial unwinding of the rear part only. As a result, theremaining stored potential energy presses the contact sleeve against thepin thereby gripping the same with a strong frictional pressure. Thispressure will remain as long as the connector parts are applied to eachother thus assuring a safe retention of the plug in its receptacle andan improvement of the electrical contact pressure.

This advantage applies even when the contact elements are worn out, thatis, if there is insuflicient'friction between pins 19 and sleeves 21.The stored potential energywill nevertheless cause pressure of the pinsagainst the sleeves and will thus maintain good electric contact.

The degree of misalignment between bores 24 and sleeves 21 can be sochosen that the turning or twisting motion, required for insertion, iseffected automatically. If the degree of misalignment is such that thetip of contact pins 19 rest against the inside sidewalls of sleeves 21,pressure on the rear of plug body 20 will tend to force the pins 19 intothe sleeves, against the pressure of the rubber which resistsdeformation. The contact pins 19 in conjunction with sleeves 21 willtherefore'act cam-like in producing a rotary action of the front part ofplug body 20 and an accompanying elongation of bores 24. Manual turningof the plug body 20 is therefore unnecessary. This manner of operationis hereinafter referred to as automatic cam action.

While the plug can be forcibly pulled out of its receptacle and viceversa it is preferable to separate the connector parts by again twistingthe rear part of plug body 20 in the same direction as it was wound foraligning the sleeves and the bores for purpose of insertion.

To facilitate twisting of the rear part relative to the front part, anannular groove 25 may be provided at the plane of junction between thefront and rear part of plug body 20.

Figs. 1 and 2 show a round plug and a round receptacle, but theinvention is also applicable to non-round shapes such as the rectangularshape frequently used for the connectors of an electric shaver.

Figs. 3 and 4 show such an arrangement. The front part 26' of the plugbody 26 has a rectangular shape and fits the well or cavity 27 formed inthe casing 27 ofthe receptacle. The shape of the plug body 26 is shownslightly exaggerated. The rectangular shape of its front is generallyblended smoothly into the rear position of the plug body.

The function of the connector of Fig. 3 will be evident from theprevious description. It suffices to state that front part 26' is firstfitted in well 27' and the rear part 26" of body 26 is then wound topermit the completion of the insertion. Automatic cam action can bearranged by suitably spaced misalignment between the front bores and thecontact sleeves inside the plug.

It will be'observed that with a non-round plug according to theinvention, the elongation of the bores in the front part of the plugbody is eliminated because the said front part is secured againstrotation by its fit inside the receptacle housing. The rear portion ofthe plug body must therefore be reduced in dimensions to an extent suchthat it can twist inside the receptacle housing as shown in broken linesin Fig. 4.

In the two embodiments previously described, the

contact pins are frictionally retained in the contact sleeves. Theprinciple of the invention also embraces a positive retention of thecontact pins in the .contact sleeves. The subsequent figures showdesigns in which the contact pins are positively locked in the contactsleeves by torsional action.

Referring now to Fig. .5, the plug 15 of these figures is similar toplug 15 of Figs. 1 and Z and the same components are designated by thesame numerals. Plug 15' is distinguished from plug 15 in that a space orcavity 3% extends laterally from the inner end of each sleeve 21 but inopposite direction.

The receptacle 16' is similar to receptacle 16 but each contact pin 19'is formed at its end into a onesidedly overhanging head or hook 19". Thetwo hooks extend in opposite directions and the diameters of both,sleeves 21 and bores 24 are slightly increased so that they will permitpassage of books 19".

To engage the connector, the forward end of plug 15' is inserted intohousing 17 until the misaligned sleeves 21 block further ingress. Thenthe rear part of plug 15' is circumferentially twisted until the sleevesand the bores are in alignment and plug 15' is pushed home. When now therear part of the plug is released thereby permitting this part to unwinditself in opposite direction each hook 19 enters its cavity 30overhanging the respective sleeve 21. At the same time, the inner wallof each sleeve is pressed against the respective contact pin. As isapparent, the two connector members are now positively locked to eachother and remain in the locked condition until they are released byturning the rear part of plug 15' in the same direction in which it waswound for insertion.

Automatic cam action can be applied to insertion and coupling, ashereinbefore described. The cam action is facilitated if the contacthook is formed so as to facilitate its entry into the contact sleeve.Such contact hook is shown by way of example at 19a in Fig. 6.

Fig. 7 shows a modification distinguished from the design of Figs. 5 and6 in the same manner'as Figs. 3 and 4 are distinguished from Figs. 1 and2, that is, the front part 20" of the plug is rectangular. The well ofthe coacting receptacle must, of course, have a cot-- respondingrectangular outline.

. The rectangular shape of the front part of the plug as shown in Figs.4 and 7 has the advantage that the front part is rotationally securednot only by the pins, but also by the fit of its own shape in the well.This affords the advantage that the constantly acting reverse torsion ismore evenly distributed within the rubber or the front part than in theound shapes of Figs. 1 and 5.

Figs. 8 and 9 and 10 show an application of the torsion principle of theinvention to a locking type of connector of conventional design, withflat, curved hoolishaped contact elements.

As is shown in Fig. 9, the male contact element in the conventionallocking receptacle has a shank 31 from which one sidedly extends a hook32. The two hooks face in opposite directions and are curved in thecircle of their circumferential distance.

' The coacting plug according to the invention is similar in principleto the connector plugs previouslydescribed in that its elastic body 33has in its front part circumferentially curved .bores 34, and in itsrear part two circumferentially curved contact sleeves. 35. -A cavity 36extends circumferentially from the rear end of each sleeve 35, the twocavities facing in opposite direction. Both, bores 34 and sleeves 35have a circumferential length such that they fit hooks 32.

The application of the connector members to each other is apparent fromthe previous description and from Fig. 10 which shows the contactelements in locked conducting engagement. As can be clearly seen in thisfigure, the contact hooks 32 overhang the contact sleeves 35 when therear part of body 33 is released after having been previously twisted topermit insertion of. the contact elements. Due to the overhang, the twoconnector members are positively locked to each other and remain in thelocked condition by the torsional action of the wound rubber body whichalso presses shanks 31 against the sleeve walls thereby improvingthecontact pressure. I I

It may be observed that the position of the locking contact elements asshown in Fig. is achieved also with locking connectors of conventionaldesign. The torsionally wound connector plug according to the inventionadds a constant spring force to the conventional locked engagement whichprevents involuntary un-twisting and disengagement and which furtherproduces positive and constant contact pressure.

Automatic cam action may be applied to this embodiment of the invention,as hereinbefore described. Its application is facilitated by shaping thecontact hooks so as to facilitate their entry into the contact sleeve,from the misaligned position in a manner similar to the one shown inFig. 6.

To release the two connector members, the rear part of plug 33 is againtwisted in the same direction as it was wound for the insertion of thecontact elements.

The plugs as hereinbefore described may be manufactured by bondingtogether two halves. However, the designs of the plugs according to theinvention also permit manufacture of the plugs in a single operation andbasically in the same manner in which standard cord connector plugs aremanufactured.

Fig. 11 shows a mold insert suitable for manufacturing a cord connectorplug as shown in Fig. 5. The insert according to this figure comprisestwo pins 50 which define mold cavities forming the bores 24. The upperpart of each pin is set ofi to form parts 50' which serve to carry thewired sleeves 21 during the molding process and to produce the requiredmisalignment of the sleeves and the bores in the body of the plug. Asthe rubber of the body should be highly elastic to permit the requiredtorsional action, the pins can be easily withdrawn upon completion ofthe molding operation.

Fig. 12 shows a mold insert similar in principle to the one justdescribed and suitable for molding cord connector plugs as shown in Fig.8. The insert of Fig. 12 has a part 52 to form bores 34, a set-off part53 to form cavities in the body receiving the contact sleeves and a hookpart 54 to form cavities 36.

The invention is also applicable to connectors with more or less thantwo contact elements.

While the invention has been described in detail with respect to certainnow preferred examples and embodiments of the invention it will beunderstood by those skilled in the art after understanding theinvention, that various changes and modifications may be made withoutdeparting from the spirit and scope of the invention, and it isintended, therefore, to cover all such changes and modifications in theappended claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. An electrical connector comprising a recessed receptacle and a plugcoacting with said receptacle, said receptacle including a pair ofcontact elements mounted in the receptacle recess in fixed spaced apartpositions and each ending in a one-sidedly enlarged head, and said plugcomprising an elastic torsionally twistable single piece connector bodyof insulation material, and a pair of elongated hollow contact membersembedded in said bodyeach for receiving the respective contact elementof the receptacle, said body including a pair of -bores each extendingfrom the outside of the body to the near edge of the respective contactmember and further including within its body a pair of detaining spaceseach transversely extending from the far end of the respective contactmember beyond the peripheral outline thereof, said contact members andsaid bores occupying in the relaxed state of said body a detainingposition relative to each other, blocking passage of the contactelements through the bores and insertion in the contact members and in atorsionally twisted state of the body a receiving position in which thecontact members and the bores are disposed relative to each other toform a passage for insertion of each contact element and passage of thehead thereof into the respective space whereby upon re;- lease of saidbody the'contact members 'andthe bores return into said detainingposition relative to each other in which the inserted contact elementsare positively detained in the contact members by the position of thehead in each respective space.

2. An electrical connector comprising a recessed receptacle and a plugcoacting with said receptacle, said receptacle including a pair ofcontact elements each mounted in the receptacle recess in a fixedposition and ending in a one-sidedly enlarged head and said plugcomprising an elastic torsionally twistable single piece connector bodyof insulation material and a pair of contact sleeves each embedded insaid body for receiving the respective contact element of thereceptacle, said body including a pair of bores each extending from theoutside of the body in axially parallel relationship with the respective sleeve and further including within its body a pair ofdetaining spaces each transversely extending from the inner end of therespective sleeve beyond the peripheral outline thereof, each sleeve andthe respective bore occupying in the relaxed state of said body anaxially misaligned but parallel position relative to each other blockingpassage of the respective contact element through the bore and insertionin the contact sleeve and in a torsionally twisted state an axiallyaligned position in which each sleeve and the respective bore form acontinuing opening for passage and insertion of the respective contactelement and passage of the head thereof into said space whereby uponrelease of the body the same unwinds towards its relaxed state in whicheach inserted contact element is positively detained in the respectivesleeve by the position of the head in the respective space.

3. An electrical connector comprising a recessed receptacle and a plugcoacting with said receptacle, said receptacle including a pair ofcontact elements each mounted in the receptacle recess in afixedposition and ending in a one-sidedly enlarged head, and said plugcomprising an elastic torsionally twistable single piece connector bodyof insulation material, part of said body fitting said recess forretention therein and the protruding part of the body being twistable ina circumferential direction relative to said retainable part, and a pairof contact sleeves each embedded in said twistable part for receivingthe respective contact element, said retainable part including a pair ofbores therethrough each extending from the front of said part parallelto the respective sleeve to the front thereof and said retainable partfurther incuding within its body a pair of retaining spaces eachtransversely extending from the inner end of the respective sleevebeyond the peripheral outline thereof, the peripheral outlines of eachbore and associated sleeve fitting the respective head for passagetherethrough, each sleeve and associated bore occupying in the relaxedstate of said part an axially misaligned but parallel position relativeto each other blocking passage of the respective contact element throughthe bore and insertion in the respective contact sleeve and in atorsionally twisted state of said body parts relative to each other anaxially aligned position in which each sleeve and associated bore form acontinuing opening for insertion of the respective contact element andpassage of the head thereof into the respective space whereby uponrelease of the body parts the same unwind toward the relaxed state inwhich the head of each contact element is positively detained in therespective space.

4. A connector according to claim 3 wherein each contact element is inthe form of a round pin shaped at its free end to form said head.

5. A connector according to claim 3 wherein each contact elementcomprises a fiat shank having at its free end a one-sided lateralextension forming said head.

6. A connector according to claim 2 wherein the portion of each headengageable with the respective contact sleeve upon insertion of therespective contact element in

